The present invention relates to sensors for monitoring a patient, and in particular to disposable sensors used for oximetry.
Numerous types of sensors may detect various aspects of a patient's physiological condition. For example, temperature could be measured, blood pressure, heart rate, etc. Optical sensors can detect characteristics such as blood oxygen saturation by directing light into a patient and then detecting the scattered reflected or transmitted light. Additionally, Ph or other characteristics of the blood may be monitored. Pulse oximeter sensors also monitor the pulse waveform resulting from the heartbeat.
Oximetry sensors can typically either be reusable sensors mounted in rigid housing, such as a clip-on sensor, or can be disposable sensors mounted on a bandaid-type material. In the disposable sensors, it is desirable to have low cost manufacturing since they will be used only a single time. At the same time, reliability needs to be maintained.
U.S. Pat. Nos. 5,469,845 and 5,246,003, assigned to Nellcor Puritan Bennett, illustrate examples of a flexible sensor using a flex circuit which can be disposable. Typically, such a sensor would include an adhesive for attaching to a patient's skin, making the sensor necessarily disposable or raising sterilization issues.
One approach for reusing a flexible sensor is set forth in U.S. Pat. No. 5,090,410, assigned to Datascope Investment Corp. This patent sets forth a disposable sleeve into which a flexible sensor can be inserted, with the sleeve having adhesive for attaching to a patient. Thus, the relatively inexpensive sleeve can be thrown away with the sensor itself being reusable. This patent mentions the importance of ensuring that the sensor itself does not come in contact with either the patient, or an adhesive, to avoid the need for sterilization.
If a sensor designed for a single use is instead inserted into a sleeve and used multiple times, a number of operating issues arise. First, it is important that the sleeve allow the sensor to be properly attached in the manner in which it was intended. In addition, reliability issues may arise since a sensor designed to withstand wrapping around a patient's appendage a single time may break down if rewrapped several times. Accordingly, it is desirable to have an improved sleeve which would not impair a sensor's designed operation, and also a flexible sensor which is reusable.